Solvent refining of lubricating oil



Patented Mar. 30, 1937 UNITED STATES PATENT OFFICE SOLVENT REFINING F LUBRICATING OIL Louis A. Clarke, Fishkill N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application April 17, 1935, Serial No. 16,753

4 Claims.

is 5 refining of mineral oil with a selective solvent. It

also contemplates a process of manufacturing lubricating oil wherein the lubricating oil stock is treated with a selective solvent liquid to separate it into fractions having desired characteristics, 1' such as high viscosity index.

The invention has particular reference to the extractive treatment of mineral lubricating oil with a solvent selected from the aryl esters of halogenated fatty acids, such as halogenated acetic, propionic and butyric acids. I have discovered that the aryl esters of these halogenated fatty acids, such as benzylchloracetate and phenylethylchloracetate, are particularly suitable as solvents for the refining of mineral lubricating oil. These compounds have the following chemical structure:

H n OHCH l Benzyln-c o o-c c on chlor- I II I acetate 01 O H OH=GH H H H GHCH l I a ff i ?-i?i- 2 $111811 01 o H H OH=CH acetate The foregoing solvent liquids have been found suitable for the treatment of mineral lubricating oil stock for the production therefrom of high viscosity index lubricating oil products.

Lubricating oil fractions, such as produced from carbon constituents as well as relatively nonparaffinic hydrocarbon constituents including naphthenic, aromatic and unsaturated hydrocarbon bodies. I have found that the paraflinic and relatively non-parafiinic constituents of lubricating oil can be separated by extractive treatment with the foregoing types of solvent liquid as, for example, benzylchloracetate.

In the application of my invention to the treatment of mineral oil for the production of a lubricating oil product, one part of the oil is mixed with from one to two parts of the solvent liquid, and this mixture is then subjected to agitation while maintained at a suitable temperature. Thereafter, the mixture, while maintained at the proper temperature, is allowed to separate into an extract and a rainnate phase. The extract phase contains the relatively non-paraffinic portion of the oil dissolved in the solvent, while the Mid-Continent crude, contain parafiinic hydrorafiinate phase comprises the undissolved paraffinic portion of the oil mixed with some of the solvent liquid.

The solvent liquid is then removed from the extract and rafi'inate phases by distillation, or by washing with other and more'volatile solvents.

' The extent to which the oil is soluble in the solvent Will depend upon the nature of the par ticular oil undergoing treatment, as Well as upon the conditions of temperature and the proportions of solvent used in making the extraction. The degree of temperature and the particular proportions of solvent to oil may be varied, depending upon the degree of extraction desired.

As a specific example, a dewaxed lubricating oil distillate obtained from Mid-Continent crude and having the tests indicated below was extracted with benzylchloracetate. The oil was extracted with about an equal volume of the solvent ata temperature of around F. The mixture was separated into extract and rafiinate phases, and the rafiinate phase, upon removal of the solvent liquid, comprised about 76% of the original charge.

The tests on the oil before extraction, and on the resulting rafilnate oil were as follows:

Before Raflinate extraction oil Gravity A. P. I 21. 3 25. 8 Saybolt universal viscosity in seconds at F 1236 774 Saybolt universal viscosity in seconds at Carbon residue percent 69 2 Viscosity index 51 77 In some instances, it may be of advantage to carry out the extraction in the presence of a modifying solvent liquid, such as benzol or a light petroleum fraction, such as propane or butane, for the purpose of facilitating the extraction and further controlling the extent thereof.

While esters of chloracetic acid have been specifically mentioned above, it is contemplated that the esters of other halogen substituted acids may be used. These include the esters of fluor, brom, and iodo acids as well as the diand tri-halogen substituted acids.

The oil may be subjected to the foregoing extraction treatment, either before or after dewaxing, or subsequent to treatment with other solvents or chemicals.

The invention is not necessarily limited to the treatment of lubricating oil distillate fractions, since the solvent may be adapted to the refining and purification of various hydrocarbon or mineral oil fractions, including naphtha, kerosene, etc, as well as residual lubricating oil fractions. The extractive treatment of mineral oil with the foregoing solvents may be carried out in either continuous countercurrent operation, or in an intermittent batch-treating operation. Extraction may be effected in a countercurrent tower type of apparatus in which the solvent is introduced near the top of a vertical tower, while the oil to be treated is introduced near the bottom of the tower. is removed from the bottom of the tower, while the rafiinate phase is removed from the top thereof.

Obviously, many modifications and variations of the invention, as hereinbefore setforth, may be made without departing from the spirit and.

scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. In the refining of mineral lubricating oil containing relatively 'parafilnic and relatively non-parafiinic constituents to separate therefrom a paraffinic portion of high viscosity index, the

.method which comprises mixing the oil with an aryl ester of a halogenated fatty acid selected from the group consisting; of phenylethylchloracetate and benzylchloracetate, forming an extract phase containing non-parafiinic constituents dissolved in the solvent, and a rafiinate phase comprising parafiinic oil of high viscosity index, and separating the two phases.

In such case, the extract phase in the solvent, and a raflinate phase comprising paraflinic oil of high viscosity index, and separating the two phases.

3. In the refining of mineral lubricating on...

containing relatively paraffinic and relatively non-paraffinic constituents to separate therefrom a paraflinic portion of high viscosity index, the method which comprises mixing the oil with phenylethylchloracetate, forming an extract phase containing non-paraffinic constituents dissolved in the solvent, and a raflinate phase comprising paramnic oil ofhigh viscosity index, and separating the twophases.

4. In the refining of hydrocarbonoil containing relatively parafflnic and relatively non-paraffinic constituents to separate the oil into fractions respectively rich in paraflinic and non-parafiinic constituents, the method which comprises mixing the oil with anaryl ester ofa halogenated fatty acid selected from the group consisting of phenyl ethyl chloracetate and benzyl chloracetate, forming'an extract phase containing nonparaflinic constituents dissolved in the solvent and a ramnate phase comprising paraflinic constituents of I the oil, and separating the two phases. I

LOUIS A. CLARKE. 

